The present invention relates to a load distributing tandem suspension assembly for supporting a chassis of a vehicle such as a truck.
Known in the art are U.S. Pat. No. 3,499,660 (Raidel), U.S. Pat. No. 3,510,149 (Raidel), U.S. Pat. No. 3,762,487 (Bilas), U.S. Pat. No. 3,921,999 (Masser), U.S. Pat. No. 4,132,433 (Willetts), U.S. Pat. No. 4,136,893 (Sweet et al.), U.S. Pat. No. 4,256,326 (Cantrell et al.), U.S. Pat. No. 4,397,478 (Jensen et al.), U.S. Pat. No. 4,676,523 (Rogers), U.S. Pat. No. 4,741,553 (Raidel, II), U.S. Pat. No. 4,856,812 (Stephens et al.), U.S. Pat. No. 4,966,387 (White, IV), U.S. Pat. No. 5,234,067 (Simard), U.S. Pat. No. 5,375,871 (Mitchell et al.), U.S. Pat. No. 5,458,360 (Raidel, Sr.), U.S. Pat. No. 5,470,096 (Baxter), U.S. Pat. No. 5,615,906 (Raidel, Sr.), U.S. Pat. No. 6,062,579 (Fortier), and U.S. Pat. No. 6,129,369 (Dudding), which show various suspension systems illustrating the state of the art, some of which are particularly intended for use in tandem axle arrangements. However, such tandem axle arrangements are generally prone to unsatisfactory load distribution during operation which may lead to undesirable or unpleasant travelling conditions. In known tandem suspension systems, the front and rear suspensions are usually identical. In those that include a middle equalizer, the equalizer may have difficulty to stabilizing under different load conditions.
An object of the invention is to provide a suspension assembly for supporting a chassis of a vehicle having a tandem axle arrangement, which allows to better distribute the load on the two axles.
Another object of the invention is to provide such a suspension assembly which is less hard on the transportation when the vehicle is in a no-load state.
Another object of the invention is to provide such a suspension assembly with an equalizer which stabilizes more easily under different loads.
Another object of the invention is to provide such a suspension assembly which can be adjusted according to different loads.
Another object of the invention is to provide such a suspension assembly which improves the traction of the vehicle under sandy or snowy conditions.
Another object of the invention is to provide such a suspension assembly which provides better comfort over long distance trucking and extends the lifetime of the vehicle.
According to the present invention, there is provided a load distributing tandem suspension assembly for supporting a chassis of a vehicle, comprising front and rear elongated spring arrangements connected to each other through an intermediate equalizer arrangement. The front spring arrangement includes a first spring element having front and rear ends, and a front axle attachment on the first spring element between the front and rear ends thereof. The front end of the first spring element is provided with a first mounting bracket for pivotal attachment to the chassis. The rear spring arrangement includes a second spring element having front and rear ends, a rear axle attachment on the second spring element at the rear end thereof, a shock absorber having an end attached to the rear end of the second spring element and an opposite end provided with a second mounting bracket for attachment to the chassis, and a guiding means for guiding the rear end of the second spring element up and down with respect to the chassis in a substantially straight course. The equalizer arrangement includes an equalizer support bracket having an upper end provided with a third mounting bracket for fixed attachment to the chassis between the front and rear spring arrangement, and an equalizer arm rockably mounted onto the equalizer support bracket about a transversal pivot. The equalizer arm has a front end pivotally receiving the rear end of the first spring element, and a rear end pivotally receiving the front end of the second spring element.
The way the suspension assembly is coupled to the vehicle along with the structure and effects of the shock absorber and the guiding means on the rear spring arrangement which interact with the front spring assembly through the equalizer arrangement causes a load distribution on the two tandem axles and provides smoother suspension.